腐殖酸对纳米氧化锆水相物化性质及生态毒性的影响

Effects of Humic Acid on Aqueous Physicochemical Properties and Ecological Toxicity of Nano-Zirconium Oxide

环境中普遍存在的腐殖酸(HA)可与工程纳米材料(ENMs)发生相互作用,而有关HA对纳米氧化锆(nZrO2)颗粒物的水环境行为及生态毒理效应的影响却鲜有报道。本文考察了一种HA类似物对nZrO2在水相介质中物化性质和淡水绿藻生长抑制毒性的影响。研究发现在有HA存在时,nZrO2在水相介质中的表面电位越负,同时其悬浮颗粒的水动力学直径越小,表明HA的存在显著地提高了nZrO2的水相分散稳定性。此外,HA浓度越高,nZrO2在水相中越趋于稳定,且该现象不依赖于时间的延长。另外,随着HA浓度的增加,低浓度的nZrO2对斜生栅藻的生长抑制毒性逐渐增加,而高浓度的nZrO2对斜生栅藻的生长抑制毒性显著降低。HA影响nZrO2藻毒性的机理与HA自身的遮光效应及抑制颗粒物诱导的氧化损伤效应有关。本文强调了天然有机质在影响ENMs的环境行为和毒理效应方面起着十分重要的作用。

Humic acid (HA), ubiquitous in natural water, can interact with engineered nanomaterials (ENMs), but studies on HA affecting on aquatic behavior and ecological toxicity of nano-zirconium oxide (nZrO2) are still limited. Herein, we investigated the effects of a HA analogy on the physicochemical properties of nZrO2 and growth inhibition toxicity to freshwater algae. Results show that increasing the mass concentration of HA decreased the zeta potentials and hydrodynamic diameters, implying that HA significantly enhanced the dispersion stability of nZrO2 in the aquatic media. It was also found that the mass concentration of HA was higher, the stability extent was greater. This process was independent on the time of settling. Furthermore, increasing the mass concentration of HA increased the growth inhibition toxicity of nZrO2 at a low concentration to Scenedesmus obliquus, whereas decreased the growth inhibition toxicity of nZrO2 at a high concentration. The intensities of the HA effects mainly correlated with the shading of HA and the alleviation of particle-induced oxidative stress. This paper highlights the important roles of natural organic matters on the behavior and effect of ENMs in the environment.